This invention relates to devices and instruments for medical examination of cavities and to devices for observation of internal surfaces of hollow bodies and tubes and more particularly to constructions of optical systems for examination and observation of spaces in medicine and engineering, particularly with respect to endoscopes. Such optical systems are used when it is necessary to transmit an internal space image for visual examination, photographing, displaying on a monitor screen.
Constructions of optical systems for observation of spaces are known in medicine and engineering. Most often optical systems contain a tube housing where observation system and illumination channel light guides are arranged. The construction elements for observation or registration are placed on one end of the flexible or rigid tube housing, the other end is introduced into a space and contains elements for image transformation and illumination elements. The observed part of the internal surface is illuminated with the help of the illumination channel and the optical observation system allows investigation of the internal space surface. Quite often it is necessary to investigate lateral space surfaces. In this case the elements allowing a change in the direction of optical observation into lateral in respect to the optical system axis are introduced.
The following inventions can serve as examples of such constructions.
In the invention according to the DE application N 3716401, Int.Cl. A 61 B 1/00 entitled xe2x80x9cEndoscope nozzlexe2x80x9d and published on Nov. 19, 1987, the nozzle is fixed with the help of a joint on an endoscope housing. It contains a lens with an element for observation direction changing relative to an optical axis of the lens and a light guide of an illumination channel. The optical axes of the observation channel and the illumination channel do not coincide with each other. That""s why the nozzle is fixed to the endoscope rigidly and one has to rotate the entire endoscope housing for observation of different surface points.
The Japanese application N 4-4567 entitled xe2x80x9cRigid endoscope of inclined visionxe2x80x9d contains a mount, an optical system for observation and a light guide. The mount and the light guide are placed in a tube housing. The optical axes of the observation and illumination system for lateral direction are deflected at an angle with respect to the lens optical axis with the help of a prism. In order to observe the entire lateral surface along the whole transverse perimeter of the investigated cavity it is also necessary to rotate the entire endoscope housing around the axis of symmetry.
xe2x80x9cFiber optic inspection devicexe2x80x9d according to U.S. Pat. No. 3,481,660 issued on Dec. 2, 1969 contains a lens in a mount and illumination lamps installed in a housing in a lateral wall of which a window is provided. The lateral observation is performed due to a reflection prism situated opposite the window. For panoramic observation of the walls in a space it is necessary to rotate the entire housing of the fiber optic inspection device. xe2x80x9cStereoscopic endoscopexe2x80x9d according to U.S. Pat. No. 3,520,587 issued on Jul. 14, 1970 contains a stereoscopic optical system for lateral observation and a lateral illumination channel fixed in the tube-shaped housing not in line. Each observation system contains a lens and a reflection prism placed opposite a window provided in a housing wall. The illumination system contains a light guide and the reflection prism. Both systems are rigidly fixed in the endoscope housing. For observation of the entire surface in the space with the help of the observation system, it is necessary to rotate the entire endoscope housing around the axis.
xe2x80x9cApparatus for visual inspection of closed machineryxe2x80x9d according to U.S. Pat. No. 4,678,290 issued on Jul. 7, 1987 contains a tube-shaped housing with a lateral window, a lateral observation optical system and a lateral illumination system. The housing is filled with inert gas which provides safety from explosion of the apparatus during usage. Both systems of observation and illumination are fixedly attached in the housing of the inspection apparatus to perform panoramic observation through rotating the entire endoscope housing connected by wires with the auxiliary equipment.
U.S. Pat. No. 4,727,859 issued on Mar. 1, 1988 xe2x80x9cRight angle detachable prism assembly for borescopexe2x80x9d discloses a device for investigation of the internal spaces contains a tube where an image transmission channel and an illumination channel are situated not in line with the tube. A head containing two closely arranged prisms installed in a common mount is connected to the tube. One prism is used for illumination of the lateral surface of the investigated space and the second prism is used for image transmission in case of lateral viewing.
In order to observe the entire surface of the space or channel using this device it is necessary to rotate the tube together with the head around the longitudinal axis which is not always convenient because the device is connected by wires with the auxiliary equipment.
The object of the declared invention is to create an optical system of lateral observation endoscope to perform panoramic observation of the internal surface of a space or channel due to rotation of only the lateral observation nozzle around the optical axis of the endoscope by an unlimited angle.
The achievement of the mentioned object will make the endoscope application more convenient and will enlarge its possibilities.
Another object of the invention is to obtain a construction where a beam of lateral illumination and a beam of lateral observation converge spatially which provides better observation conditions.
Another object of the invention is to make an endoscope application more convenient as well as to improve the quality of optical observation of the internal space or tube with the help of the endoscope.
Other objects and advantages of the present invention will be disclosed when considering the detailed description and drawings.
An optical system of the lateral observation endoscope is provided in the form of a tube where the lens is installed along the axis of symmetry and a longitudinal fiber illumination light guide is arranged along the entire internal surface of the tube.
The lateral observation nozzle is installed on the tube, whose housing is tube-shaped with a window in the lateral wall and is installed on the tube in line with the possibility of unlimited rotation around the tube for panoramic lateral observation.
The lateral observation nozzle is provided with a unit of two reflection prisms, one of which is meant for lateral observation and the other prism for lateral illumination. The lateral observation prism is incorporated into the lateral illumination prism body in such a way that each of two refracting faces of one prism lies in the plane of the matched faces of another prism. In this case, the refracting faces of the lateral- illumination prism cover faces of the lateral observation prism on three sides. In this case the illumination beam illuminates more uniformly the observed surface section which is situated in the view field of the lateral observation prism.
The prism unit is installed in the housing of the nozzle in such a way that one pair of the matched refracting faces of both prisms lies in the plane perpendicular to the optical axis of the lens, in this case the-refracting face of the lateral observation prism is arranged opposite the lens installed along the tube symmetry axis and the matched with the face of the lateral illumination gob prism being arranged opposite the end face of the longitudinal fiber illumination light guide. Another pair of refracting faces adjacent to the mentioned pair, is oriented towards the lateral window provided in the wall of the nozzle housing.
The integration of the lateral observation prism with the lateral illumination prism in the prism unit along the entire surface of their mutual contact is opaque. That""s why light from the lateral illumination prism does not penetrate to the lateral observation prism. The diaphragm is arranged on the nozzle from the side facing the mentioned lens, and is in the form of a figure overlapping the face of the lateral observation prism facing the lens and contains a hole in line with the optical axis of the lens. The diaphragm prevents penetration of scattered light from the longitudinal fiber illumination light guide to the lateral observation prism.
There is a visor in the construction of the nozzle which is provided from the opaque sheet material in the form of a circle segment installed on the nozzle from the side of the longitudinal fiber light guide and overlaps that part which projects beyond the overall dimensions of the prism unit from the side of the lateral window provided in the wall of the nozzle housing. The visor prevents the face of the lateral observation prism presented to the lateral window in the wall of the nozzle housing from illumination by the beams coming from the part of the fiber light guide which projects beyond the overall dimensions of the prism unit.
Due to the fact that the lens is installed along the axis of symmetry in the endoscope tube, the longitudinal fiber illumination light guide is situated coaxial along the entire internal surface of the tube and the nozzle provided with the prism unit is installed on the endoscope tube with the possibility of unlimited rotation around the tube, it is possible to perform panoramic observations without resort to rotation of the entire endoscope. It is possible to rotate the nozzle using the clamp provided on the external surface of the nozzle housing.
In the prism unit, the lateral observation prism is incorporated into the body of the lateral illumination prism in such a way that the refracting faces of one prism lie in the planes of the matched faces of another prism, the refracting faces of the lateral illumination prism covering the refracting face of the lateral observation prism on three sides. Due to this fact, the illumination beams illuminate more uniformly the whole section of the observed surface being in the view field of the lateral observation prism.
There is no mixing of optical flows of illumination and observation channels because the integration of the lateral observation prism and the lateral illumination prism in the unit along the entire surface of their mutual contact is opaque.
The reflecting face of the lateral observation prism and the reflecting face of the lateral illumination prism can be provided with a light reflecting coating.
The endoscope application becomes more convenient and the quality of surface image transmission of the investigated space or channel is improved.
The prism unit containing the lateral observation prism and the lateral illumination prism can be provided in different ways.
In a first variant, the main cross-section of the lateral observation prism has the form of a right-angled triangle. The lateral surface of the lateral illumination prism is cylindrical according to the form of the aforementioned tube-shaped nozzle housing and is provided with a light reflecting coating. This variant of the prism unit contains the least number of components.
In a second variant, the lateral observation prism incorporated into the body of the lateral illumination prism is in the form of a round cylindrical body, one end face of which is upright and the other inclined to the axis of symmetry. A longitudinal flat shear provided on the lateral surface of the cylindrical body, in this case the upright end face, and adjacent lateral longitudinal flat shear are the refracting faces of the lateral observation prism. The inclined end face of the cylindrical body is the reflection face of the lateral observation prism.
In this variant, the lateral illumination prism is built-up from the tube element and the end attachment. The one end of the tube element is upright and its plane coincides with the plane of the upright end face of the cylindrical body of the lateral observation prism. The second end face of the tube element is inclined to the axis of symmetry and its plane coincides with the plane of the inclined end face of the cylindrical body of the lateral observation prism. The end attachment is in the form of an inclined cylinder with the diameter equal to the external diameter of the tube element and with both end faces inclined to the same side relative to the axis of symmetry.
The end attachment by its one end face is attached to the inclined end face of the aforementioned tube element by optically transparent adhesive. The, longitudinal flat joint shear is provided in the wall of the tube element and on the lateral surface of the end attachment whose plane coincides with the plane of the longitudinal shear of the mentioned cylindrical body of the lateral observation prism arranged in the tube element. The upright end of the tube element and the adjacent to it longitudinal flat joint shear of the tube element and the end attachment are the refracting faces of the lateral illumination prism. The inclined external end face of the end attachment is the reflection face of the lateral illumination prism. The lateral round cylindrical joint surface of the tube element and the end attachment of the lateral illumination prism is provided with a light reflecting coating.
In a third variant, the lateral observation prism incorporated into the body of the lateral illumination prism is in the form of a round cylindrical body in the same way as in the second variant.
The lateral illumination prism is built-up from the tube element and the end insert.
The internal diameter of the tube element corresponds to the external diameter of the aforementioned cylindrical body of the lateral observation prism. The one end face of the tube element is upright and its plane coincides with the plane of the upright end face of the cylindrical body of the lateral observation prism, the second end face of the tube element is inclined to the axis of symmetry.
Behind the inclined end face of the cylindrical body of the lateral observation prism the cylindrical end insert is installed in the tube element by means of an optically transparent adhesive the diameter of which is equal to the internal diameter of the tube element and the plane of the external end face of the end insert coincides with the plane of the inclined end face of the tube element.
The longitudinal flat joint shear is provided jointly in the wall of the tube element and on the lateral surface of the end insert, its plane coincides with the plane of the longitudinal shear of the cylindrical body of the lateral observation prism arranged in the tube element. The upright end of the tube element and the adjacent lateral longitudinal flat joint shear of the tube element and the end insert are the refracting faces of the lateral illumination prism.
Arranged in the same plane, the mentioned inclined end face of the tube element and the inclined end face of the end insert are the reflecting faces of the lateral illumination prism. The lateral external surface of the tube element of the lateral illumination prism is provided with a light reflecting coating.
The second and the third variants of the prism unit embodiment contain more components but they are more adaptable to streamlined production.